Does the writer write incorrectly in this paragraph?

I have a confusing paragraph about women (i know this topic may be sensitive and sexist, but i need to do that because i was requested). Here is the paragraph:
'There are no rules you need to follow or actions you need to take prior to the sex to somehow steer toward a particular type of relationship. People who do not know what they are talking about believe you need to date longer to get to know each other deeply first if you want what they call a “more serious” relationship for instance, but that is simply not the case. If you want a long-term relationship, you can and should decide it after having had sex, without rushing into it. There is nothing wrong with wanting a long-term relationship with one woman, but a man would not commit to one woman quickly, only a desperate male would, as such a hasty decision signals that the male needs her not only wants her.
This approach is also a lot easier than changing your manners all the time, and it assures that you will not end up in a long-term relationship with a female who is no fun in bed'
Do you know why the writer said ' This approach is also a lot easier than changing your manners all the time', because i don't see the writer talked about 'manner' in previous paragraph. i think there's no relation between 'This approach' and ' changing your manner'. Does the writer write incorrectly? Can you explain it? thank!